Climate slowdown? Just wait until the wind changes

POWERFUL winds in the Pacific are largely responsible for the recent slowdown in global warming. The intense winds have encouraged heat to sink into the oceans. But as soon as the winds die down, the heat will escape and warming will resume.

Over the past 20 years, the trade winds that gust westwards across the Pacific have soared to unprecedented strengths. The strongest winds are now twice as powerful.

These winds far exceed climate modellers’ predictions. So Matthew England from the University of New South Wales in Sydney, Australia, and colleagues decided to see what would happen if they factored actual wind levels into the models.

They found that adding five years of strong trade winds created powerful ocean currents that buried the warm surface water, bringing cooler water to the surface. Those cooler waters reproduced the current warming hiatus (Nature Climate Change, doi.org/rdt). “The missing wind can account for the hiatus in its entirety,” says England.

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Last year Yu Kosaka and Shang-ping Xie of the Scripps Institution of Oceanography in California showed that cool surface waters in the Pacific could explain the hiatus (Nature, doi.org/rcp). But nobody knew why those waters were so cool. “This provides a mechanism,” says Kosaka.

A repeating weather pattern called the Interdecadal Pacific Oscillation may explain the winds’ strength. In its current state, the IPO should produce strong winds, says England. “But the models capture less than half the magnitude at best.”

England says that the winds will return to normal. The warm water is only about 125 metres down, so we could see rapid warming as it resurfaces. It is not clear when that will happen, but if the hiatus follows the pattern of the IPO, it may only last another five or six years, England says.

This article appeared in print under the headline “Warming is only on hold until the wind changes”